Overview:This Science in Action article on endosymbiosis explores the career of microbiologist, Lynn Margulis and how an unlikely idea overcame strong resistance within the scientific community and finally came to be an accepted part of evolutionary theory.

Author/Source:UCMP

Grade:College

Discipline:Life Science, Nature and Process of Science

Time:One period

Teaching tips:Science textbooks are full of content that represents our current understanding of the natural world and how it works. But where did that content come from? This Science in Action story about endosymbiosis provides an excellent opportunity to reinforce the scientific enterprise and how knowledge is built – even in the face of strong initial resistance within the scientific community.
Use the story to make the following aspects of the nature of science explicit to your students:
- Science can test hypotheses about events that happened long ago.
- Scientific ideas are tested with multiple lines of evidence.
- Scientific ideas evolve with new evidence; however, well supported scientific ideas are not tenuous.
- Through a system of checks and balances, the process of science can overcome individual biases.
- Evidence is the most important arbiter of which scientific ideas are accepted.
Encourage students to use the How Science Works Flowchart to map to follow the efforts of Lynn Margulis as she sought to evaluate the scientific evidence.